Elastomeric bilayer armor incorporating surface-hardened substrates

Abstract

An armor system is formed of a substrate including an underlying substrate layer of less hard material and including a thin layer of harder material at a first face of the substrate, and an elastomeric material layer positioned at the first face of the substrate. The increased hardness of the thin hard layer increases the penetration resistance of the armor by increasing the elastomer's contribution to penetration resistance. The properties of the substrate can be independently selected, allowing the use of substrates with lower hardness, increasing the armor's ballistic performance, and lowering the weight of the armor.

What is claimed as new and desired to be protected by Letters Patent of the United States is: 
     
         1 . An armor system comprising:
 a substrate including an underlying substrate layer of less hard material and including a thin layer of harder material at a first face of the substrate;   an elastomeric material layer positioned at the first face of the substrate.   
     
     
         2 . The armor system of  claim 1 , wherein the underlying substrate material is steel. 
     
     
         3 . The armor system of  claim 1 , wherein the underlying substrate material is aluminum. 
     
     
         4 . The armor system of  claim 1 , wherein the thin layer of harder material is a harder coating material applied to the underlying substrate. 
     
     
         5 . The armor system of  claim 1 , wherein the thin layer of harder material is formed by surface hardening the substrate material by at least one of carburizing, nitriding, carbonnitriding, nitrocarburizing, boriding, titanium-carbon diffusion, the Toyota diffusion process, flame hardening, induction hardening, laser hardening, electron beam hardening, ion implantation, heat treating with arc lamps, or mechanical work hardening. 
     
     
         6 . The armor system of  claim 1  wherein the elastomeric material layer comprises at least one of polyisobutylene (PIB), PU-1 polyurea, PU-2 polyurea, polynorbornene (PNB) 24, nitrile rubber (NBR), and atactic polypropylene. 
     
     
         7 . The armor system of  claim 1 , wherein the elastomeric material layer is at least two millimeters thick. 
     
     
         8 . The armor system of  claim 1 , wherein the elastomeric material layer is at least a few millimeters thick. 
     
     
         9 . The armor system of  claim 1 , wherein the underlying substrate material has a Brinell hardness of less than 500 Brinell units and the thin harder layer has a hardness of at least 900 Brinell units. 
     
     
         10 . The armor system of  claim 1 , wherein the thin harder layer has a hardness of at least 25 Brinell hardness points above that of the underlying substrate material. 
     
     
         11 . The armor system of  claim 1 , wherein the thin hard layer is formed by oxidizing and polishing the surface of a high hardness steel substrate. 
     
     
         12 . The armor system of  claim 1 , wherein the thin hard layer is formed by sandblasting and polishing the surface of a high hardness steel substrate. 
     
     
         13 . The armor system of  claim 1 , wherein the thin hard layer is formed by oxidizing and polishing the surface of an ultra high hardness steel substrate.
 The armor system of  claim 1 , wherein the thin hard layer is formed by sandblasting and polishing the surface of an ultra high hardness steel substrate.   
     
     
         14 . The armor system of  claim 1 , wherein the thin harder layer has a thickness of between 0.02 mm and 0.05 mm. 
     
     
         15 . The armor system of  claim 1 , wherein the thin harder layer has a thickness between 0.005 inches and 0.01 inches. 
     
     
         16 . The armor system of  claim 1 , wherein the properties of the substrate are selected independently of the thin hard layer and the elastomeric material layer.